1. Field of the Invention
This invention relates to a room temperature curable organopolysiloxane composition, particularly to a dealcoholation type room temperature curable organopolysiloxane composition.
2. Description of Prior Art
Various room temperature curable organopolysiloxane compositions (hereinafter abbreviated as RTV siloxane composition) have been known in the art.
Among them, compositions comprising crosslinking agents such as methyltrimethoxysilane or the like and a catalyst such as organic titanium compounds or organic titanium chelating compounds added to an organopolysiloxane having hydroxyl groups at terminal ends of its molecular chain will form rubbery organopolysiloxanes with generation of alcohol during curing. The compositions are not corrosive without generation of stimulative odor, and have been widely used as adhesives in electrical or electronic industries.
However, the dealcoholation type RTV siloxane composition of this kind generally has the disadvantages of slow curing rate, poor internal curability and poor storability, and has the drawback in the case of long term storage even if it may be under anhydrous state that it cannot be cured when used.
For this reason, it has been proposed to add a silane compound having two alkoxy groups as the so called silane scavenger to the dealcoholation type RTV siloxane composition, thereby improving its storage stability and curability.
Also, as a dealcoholation type RTV siloxane composition, there has been proposed one comprising a diorganopolysiloxane terminated with hydroxyl groups at its ends of the molecular chain, and, in addition thereto, an alkoxysilane or a partial hydrolysis product thereof, a guanidinyl-substituted alkylalkoxysilane represented by the following formula: EQU [(CH.sub.3).sub.2 N]C.dbd.N(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3
and an organic tin compound (see Japanese Pre-examination Patent Publication (KOKAI) No. 52351/1983).
However, in the composition wherein the above-mentioned silane compound having two alkoxy groups is added as the silane scavenger, for improvement of storage stability, hydrolyzable groups other than the two alkoxy groups of the silane compound are required to be made those having high reactivity such as amide group, amino group, etc. However, since these groups bring about corrosiveness and odor, the RTV siloxane composition can not be used as adhesives in electrical, electronic industries.
Also, the composition described in Japanese Pre-examination Patent Publication (KOKAI) No. 52351/1983 is stated to have good storage stability. But, in fact, as free alcohol forms through the reaction of silanol groups in the diorganopolysiloxane with alkoxysilane or partial hydrolysis product thereof and remains in the composition, storability is extremely poor.